Knee walker with four-wheel steering

ABSTRACT

A knee walker with four-wheel steering. The knee walker includes a frame, at least one front axle assembly, at least one rear axle assembly, a kneeling pad assembly, and a steering system. The steering system is configured to turn the rear axle assembly in the opposite direction from the front axle assembly. The opposing angles of the front and rear wheels enable the knee walker to perform tighter turns by eliminating rear wheel drag.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/861,376 filed Jun. 14, 2019, the entirety ofwhich is hereby incorporated herein by reference for all purposes.

TECHNICAL FIELD

The present invention relates generally to the field of ambulatorydevices, and more particularly to a knee walker or knee scooter withfour-wheel steering for improved maneuverability and stability inturning.

BACKGROUND

An injury to the knee, lower leg, ankle, or foot can have life alteringconsequences. In many cases, a person suffering such an injury may becondemned to weeks, or longer, of misery on crutches or a wheelchair,often making normal everyday activities painful, dangerous and, in manycases, difficult or impossible.

Prior to the invention of knee walkers or knee scooters, many patientswith such injuries had no choice but to limit activity during recoveryand use crutches or a wheelchair when necessary. Unfortunately, neitherchoice allows the patient to move freely and go about the patient'sdaily routine. When using crutches, the patient's arms support thepatient's body weight and the patient's arms and upper back are used formobility. Similarly, a patient in a wheelchair must rely solely on thepatient's upper body strength and the patient is restricted to a seatedposition. And it can be difficult to open and close doors, maneuverthrough tight spaces, and to carry items when using crutches or awheelchair.

On a knee walker, the larger muscles of the patient's legs are leveragedinstead. Using these larger muscles results in less upper body pain,less patient fatigue, and less chance of re-injury should the patientlose balance and the injured leg suffers an accidental impact. A kneewalker also provides the patient with the ability to be hands-free whilestanding still enabling the user to accomplish many daily tasks at home,at work or on the go.

While a standard knee walker provides many benefits over crutches andwheelchairs, some users would prefer greater maneuverability andstability than presently known knee walkers provide. It is to theprovision of an improved knee walker meeting these and other needs thatthe present invention is primarily directed.

SUMMARY

In example embodiments, the present invention provides an improved kneewalker (also referred to as a knee scooter) or other mobility orambulatory care device that enhances maneuverability and stability inoperation. In example forms, the improved knee walker includes afour-wheel steering system to control the turning or articulation ofboth the front wheels and the rear wheels. In example embodiments, thesteering system includes a linkage coupling turning of the front wheelswith turning of the rear wheels, for example turning the front wheels inthe direction the user steers the walker's handlebar and turning therear wheels in the opposite direction. In this manner, a tighter turningradius may be provided, and stability in turns may be improved due toshifting of the yaw axis toward the center of gravity.

In one aspect, the present invention relates to knee walkers or othermobility or ambulatory care devices with four-wheel steering. The kneewalker includes a body frame, at least one front axle assembly, at leastone rear axle assembly, a knee-pad assembly, and a steering system. Thesteering system preferably includes a linkage mechanism configured toturn the front axle assembly in a first direction and the rear axleassembly in an opposite second direction. The opposing turn angles ofthe front and rear wheels enable the knee walker to perform tighterturns by eliminating rear wheel drag.

In another aspect, the invention relates to four-wheel steering systemsfor knee walkers or other mobility or ambulatory care devices. Thefour-wheel steering system uses one or more linking members such as aplurality of cables and/or tie rods to control the turning of the frontwheels and the rear wheels together. In another form, the four-wheelsteering system uses only cables or only ties rods to achieve the samepurpose. In yet another form, the four-wheel steering system uses asystem of gears or other linking elements to control the turning of thefront and rear wheels, or axles together.

In still another aspect, the invention relates to a four-wheel steeringsystem for a knee walker or other mobility or ambulatory care devicewith a pivoting rear axle assembly. The rear axle assembly, as a whole,is configured to pivot relative to the knee walker body frame. The rearwheels mounted to the rear axle assembly, on the other hand, areconfigured not to pivot relative to the rear axle assembly. Thefour-wheel steering system includes tie rods to control the turning ofthe front and rear axle assemblies.

In another aspect, the invention relates to a method of steering a kneewalker or other ambulatory device by linking turning of the rear wheelsto turning of the front wheels.

These and other aspects, features and advantages of the invention willbe understood with reference to the drawing figures and detaileddescription herein, and will be realized by means of the variouselements and combinations particularly pointed out in the appendedclaims. It is to be understood that both the foregoing generaldescription and the following brief description of the drawings anddetailed description of example embodiments are explanatory of exampleembodiments of the invention, and are not restrictive of the invention,as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a knee walker in use according to an exampleembodiment of the present invention.

FIG. 2 is an isometric view of the knee walker of FIG. 1.

FIG. 3A is a bottom view of the knee walker of FIG. 1 in a right turnconfiguration.

FIG. 3B is a bottom view of the knee walker of FIG. 1 in a left turnconfiguration.

FIG. 4 shows additional details of a steering system and front axleassemblies at a front portion of the knee walker of FIG. 1.

FIG. 5 shows additional details of the steering system and rear axleassemblies at a rear portion of the knee walker of FIG. 1.

FIG. 6 is a bottom view of the knee walker according to another exampleembodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

The present invention may be understood more readily by reference to thefollowing detailed description of example embodiments taken inconnection with the accompanying drawing figures, which form a part ofthis disclosure. It is to be understood that this invention is notlimited to the specific devices, methods, conditions or parametersdescribed and/or shown herein, and that the terminology used herein isfor the purpose of describing particular embodiments by way of exampleonly and is not intended to be limiting of the claimed invention. Anyand all patents and other publications identified in this specificationare incorporated by reference as though fully set forth herein.

Also, as used in the specification including the appended claims, thesingular forms “a,” “an,” and “the” include the plural, and reference toa particular numerical value includes at least that particular value,unless the context clearly dictates otherwise. Ranges may be expressedherein as from “about” or “approximately” one particular value and/or to“about” or “approximately” another particular value. When such a rangeis expressed, another embodiment includes from the one particular valueand/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another embodiment.

With reference now to the drawing figures, wherein like referencenumbers represent corresponding parts throughout the several views, FIG.1 shows a user on a knee walker 10 according to an example embodiment ofthe present invention. The knee walker 10 generally comprises a bodyframe 20, a cushion or kneeling-pad assembly 30, front axle assemblies40′ and 40″, rear axle assemblies 50′ and 50″, and a four-wheel steeringsystem 60. In some example embodiments, knee walker 10 further comprisesa body frame cover or chassis 19.

The four-wheel steering system 60 allows the user to control thedirectional orientation or turning of the front axle assemblies 40′ and40″ and rear axle assemblies 50′ and 50″ in tandem. Generally, the frontaxle assemblies 40′ and 40″ rotate in a first rotational or angulardirection while the rear axle assemblies 50′ and 50″ rotate in anopposite second rotational or angular direction. For example, as thefront axle assemblies 40′ and 40″ are rotated counter-clockwise, therear axle assemblies 50′ and 50″ are caused to rotate in the opposite,clockwise direction, as shown in FIG. 3A. Conversely, if the front axleassemblies 40′ and 40″ are rotated clockwise, the rear axle assemblies50′ and 50″ are rotated in the opposite, counter-clockwise direction, asshown in FIG. 3B. The opposing rotational alignment of the front axleassemblies 40′ and 40″ and the rear axle assemblies 50′ and 50″ enablesthe knee walker to achieve a tighter or smaller turning radius comparedto traditional knee walkers with two-wheel steering. In the neutralposition, the front axle assemblies 40′ and 40″ and rear axle assemblies50′ and 50″ are collaterally aligned, as shown in FIG. 2.

As shown in FIGS. 1 and 2, body frame 20 generally comprises a head tubeor sleeve 22, front crossbar or cross-member 24, a center crossbar orcross-member 26, a knee-pad tube or sleeve 28, and a rear crossbar orcross-member 27. Body frame 20 generally comprises a tubular structureand is preferably constructed from a rigid material, including, but notlimited to, metals, polymers, fiber-reinforced plastics, and/orcombinations thereof. As shown in FIG. 2, head tube 22 comprises afirst, top end and a second, bottom end. At its second, bottom end,headtube 22 is welded, or otherwise affixed, to the front crossbar 24.In example embodiments, the front crossbar 24, spanning about 12-30inches, preferably about 12-15 inches, or more preferably about 13.5inches, is affixed at its center to the bottom end of head tube 22 andextends substantially perpendicular thereto. According to exampleembodiments, the front crossbar 24 has an arced or curved profile.However, the front crossbar 24 may comprise other profiles such aslinear, angled, curved or any combination thereof. In exampleembodiments, front crossbar 24 comprises a left, proximal end 24A′ and aright, distal end 24A″ where each end comprises a cylindrical hinge orpivot body about which front axle assemblies 40′ and 40″ are hingeablysecured as described below.

As best shown in FIG. 4, front axle assemblies 40′ and 40″ are pivotallymounted to the left and right ends 24A′, 24A″ of the front crossbar 24,respectively. In the depicted embodiment, the left front axle assembly40′ comprises a left front axle bracket 41′ having generally a C-shapedprofile. The left front axle bracket includes a vertical portion orsection having a top end and a bottom end. At its top end, the leftfront axle bracket includes a top prong or member which extendstransversely from the vertical portion to a free end. The verticalportion also includes a bottom prong or member which extendstransversely from the vertical portion to a free end in the same generaldirection of the top prong. The top and bottom members are generallypositioned such that they are substantially parallel to one another andsubstantially perpendicular to the vertical portion. Space or gap isprovided between the top and bottom horizontal prongs, the space or gaphaving sufficient area to receive the left end 24A′ of the frontcrossbar 24. In depicted embodiments, the free ends of the top andbottom prongs are concentrically aligned with and pivotally mounted tothe left end 24A′ of the front crossbar 24, for example by a bolt orpivot pin.

In the example embodiments, the left front axle bracket 41′ furthercomprises a left front axle 42′ on which left front wheel 43′ isrotatably mounted. The left front axle is generally secured to thevertical portion of the axle bracket and extends transversely from thevertical portion in a direction opposite the top and bottom horizontalprongs. In example embodiments, the left front axle 42′ is a bolt oraxle pin having a head end and a threaded end, wherein the bolt issecured to the left front axle bracket 41′ by its threaded end and theleft front wheel 43′ is rotatably mounted on the bolt between the headand threaded ends. In other example embodiments, the left front axle 42′may be a fixed component of the left front axle 41′ which extendstransversely therefrom. Axle bracket 41′ also includes a front tie-rodconnection tab or member 44′, as best shown in FIG. 4. The front tie-rodconnection tab 44′ is configured for mounting thereon one end of a fronttie-rod 67′ as described further below.

Similarly, in the depicted embodiment, the right front axle assembly 40″comprises a right front axle bracket 41″ having generally a C-shapedprofile. The right front axle bracket 41″ includes a vertical portion orsection having a top end and a bottom end. At its top end, the rightfront axle bracket includes a top prong or member which extendstransversely from the vertical portion to a free end. The verticalportion also includes a bottom prong or member which extendstransversely from the vertical portion to a free end in the same generaldirection of the top prong. The top and bottom members are generallypositioned such that they are substantially parallel to one another andsubstantially perpendicular to the vertical portion. Space or gap isprovided between the top and bottom horizontal prongs, the space or gaphaving sufficient area to receive the right end 24A″ of the frontcrossbar 24. In depicted embodiments, the free ends of the top andbottom prongs are concentrically aligned with and pivotally mounted tothe right end 24A″ of the front crossbar 24, for example by a bolt orpivot pin.

In the example embodiments, the right front axle bracket 41″ furthercomprises a right front axle 42″ on which right front wheel 43″ isrotatably mounted. The right front axle is generally secured to thevertical portion of the axle bracket and extends transversely from thevertical portion in a direction opposite the top and bottom horizontalprongs. In example embodiments, the right front axle 42″ is a bolt oraxle pin having a head end and a threaded end, wherein the bolt issecured to the right front axle bracket 41″ by its threaded end and theright front wheel 43″ is rotatably mounted on the bolt between the headand threaded ends. In other example embodiments, the right front axle42″ may be a fixed component of the left front axle 41′ which extendstransversely therefrom. Axle bracket 41″ also includes a front tie-rodconnection tab or member 44″, as best shown in FIG. 4. The front tie-rodconnection tab 44″ is configured for mounting thereon one end of a fronttie-rod 67″ as described further below.

The center crossbar 26, having a front, proximal end and a rear, distalend, extends between the head tube 22 and rear crossbar 27. At its frontend, center crossbar 26 is welded, or otherwise attached, to thevertical head tube 22 and extends generally transversely therefrom. Atits rear end, center crossbar 26 is welded, or otherwise affixed, to thecenter of rear crossbar 27. In example embodiments, the center crossbarspans about 19-22 inches, or preferably about 20-21 inches, or morepreferably about 20.5 inches. In the depicted embodiment, the centercrossbar 26 is attached to and extends transversely from near the topend of head tube 22. In alternative embodiments, the center crossbar 26may be attached to the bottom end of the head tube 22, the center of thehead tube 22, or any position or location along the length of the headtube 22. In yet other example embodiments, there may be multiple centercrossbars or support bars arranged in various configurations forincreased stability and rigidity.

The center crossbar 26 also comprises a knee-pad tube or sleeve 28configured to receive the knee-pad assembly 30 as described below. Theknee-pad tube 28 comprises a top end and a bottom end and is hollowtherethrough. The knee-pad tube generally extends transversely from thecenter crossbar and substantially perpendicular to the ground or ridingsurface. The location of the knee-pad tube 28 may vary along the lengthof the center crossbar 26 between its front and rear ends. Knee-pad tube28 may also include a locking pin hole 29, a post collar lock, or othersimilar locking mechanisms to hold the knee-pad assembly in place duringuse. According to example embodiments, the knee-pad tube 28 ispositioned on the center crossbar 26 at about 10-20 inches, preferablyabout 12-18 inches, or more preferably about 14-16 inches, from headtube 22 and is marginally angled relative to the ground. Alternatively,the knee-pad tube 28 is secured to the center crossbar 26 wherein thedistance between the knee-pad tube and the front end of the crossbar isequal to or greater than, for example about 1.5-2 times, the distancebetween the knee-pad tube and the back end of the crossbar.

The cushion or knee-pad assembly generally comprises a cushion 31, acushion base plate 32, and a cushion post 33. In use, the user placesone knee on the cushion or knee-pad 31 to reduce the pressure or forceapplied to the knee, lower leg, ankle, and/or foot. The cushiongenerally comprises a pliable or resilient core encased in an elasticshell or casing. According to the example embodiment, the cushion ismade from resilient foam enveloped in a synthetic leather shell. Inother example embodiments, the cushion core may comprise fillers such asrubbers, gels, natural and/or synthetic fibers, or other suitablematerials known in the art. Similarly, the cushion casing may beconstructed from natural or synthetic leather, natural or syntheticfibers, rubbers, or other suitable materials known in the art.

Cushion 31 generally comprises a top surface, a bottom surface, and aside surface between the peripheries of the top and bottom surfaces.According to example embodiments, the top surface of cushion 31 iscontoured to provide greater support and stability. The cushion baseplate or panel 32 is secured to the bottom surface of cushion 31 therebyproviding structure and support to the cushion. The cushion post orcolumn 33 is a tubular member secured to the cushion base plate 32. Thecushion column 33 extends transversely from the cushion base plate 32 inthe direction opposite cushion 31. The cushion column 33 comprises aplurality of through-holes 34 spaced equally apart along its length. Thethrough-holes 34 are configured to align with the locking pin hole 29 onknee-pad tube 28. In example embodiments, the knee-pad assembly 30 issecured to the body frame 20 by inserting the cushion post 33 intoknee-pad tube 28 and locking the knee-pad assembly 30 to the body frame20, for example by using a locking pin 25. The height of the knee-pad orcushion 31 may be adjusted between a plurality of predeterminedintervals by aligning the appropriate cushion column through-hole 34 tothe locking pin hole 29 and securing the position with locking pin 25.In alternative embodiments, locking pin 25 may be replaced with, or usedin addition to, other post locking mechanisms known in the art,including, but not limited to, locking knobs, locking buttons, postclamps, and split collar locks. In example embodiments, the height ofcushion 31 is adjustable between about 12-26 inches, or preferably about16-22.5 inches, from the ground or riding surface.

The rear crossbar 27 is affixed at its center to the distal end ofcenter crossbar 26 and extends substantially perpendicular thereto. Inexample embodiments, the rear crossbar 27, comprising a left, proximalend 27A′ and a right, distal end 27A″, spans about 4-7 inches,preferably about 4.5-6.5 inches, or more preferably 5.5 inches. At eachend, rear crossbar 27 comprises a cylindrical hinge or pivot body aboutwhich rear axle assemblies 50′ and 50″ are hingeably secured asdescribed below. According to example embodiments, the rear crossbar 27has a linear profile. However, the rear crossbar 27 may comprise otherprofiles such as arced, angled, curved or any combination thereof.

As shown in FIGS. 2 and 5, the rear axle assemblies 50′ and 50″ arepivotally attached to the left, proximal end 27A′ and right, distal end27A″ of the rear crossbar 27, respectively. In the depicted embodiment,the left rear axle assembly 50′ comprises a left rear axle bracket 51′having generally a C-shaped profile. The left rear axle bracket includesa vertical portion or section having a top end and a bottom end. At itstop end, the left rear axle bracket includes a top prong or member whichextends transversely from the vertical portion to a free end. Thevertical portion also includes a bottom prong or member which extendstransversely from the vertical portion to a free end in the same generaldirection of the top prong. The top and bottom members are generallypositioned such that they are substantially parallel to one another andsubstantially perpendicular to the vertical portion. Space or gap isprovided between the top and bottom horizontal prongs, the space or gaphaving sufficient area to receive the left end 27A′ of the rear crossbar27. In depicted embodiments, the free ends of the top and bottom prongsare concentrically aligned with and pivotally or rotationally mounted tothe left end 27A′ of the rear crossbar 27, for example by a bolt orpivot pin.

According to example embodiments, the left rear axle bracket 51′ furthercomprises a left rear axle 52′ on which left rear wheel 53′ is rotatablymounted. The left rear axle is generally secured to the vertical portionof the axle bracket and extends transversely from the vertical portionin the direction opposite the top and bottom horizontal prongs. Inexample embodiments, the left rear axle 52′ is a bolt or axle pin havinga head end and a threaded end, wherein the bolt is secured to the leftrear axle bracket 51′ by its threaded end and the left rear wheel 53′ isrotatably mounted on the bolt between the head and threaded ends. Inother example embodiments, the left rear axle 52′ may be a fixedcomponent of the left rear axle 51′ which extends transverselytherefrom. Axle bracket 51′ also includes a rear tie-rod connection tabor member 54′ and a center tie-rod connection tab or member 55′, as bestshown in FIG. 5. The rear tie-rod connection tab 54′ is configured formounting thereon one end of a rear tie-rod 68 as described furtherbelow. Similarly, the center tie-rod connection tab 55′ is configuredfor mounting thereon one end of a left center tie-rod 65′ as describedbelow.

Similarly, in example embodiments, the right rear axle assembly 50″comprises a right rear axle bracket 51″ having generally a C-shapedprofile. The right rear axle bracket includes a vertical portion orsection having a top end and a bottom end. At its top end, the rightrear axle bracket includes a top prong or member which extendstransversely from the vertical portion to a free end. The verticalportion also includes a bottom prong or member which extendstransversely from the vertical portion to a free end in the same generaldirection of the top prong. The top and bottom members are generallypositioned such that they are substantially parallel to one another andsubstantially perpendicular to the vertical portion. Space or gap isprovided between the top and bottom horizontal prongs, the space or gaphaving sufficient area to receive the right end 27A″ of the rearcrossbar 27. In depicted embodiments, the free ends of the top andbottom prongs are concentrically aligned with and pivotally orrotationally mounted to the right end 27A″ of the rear crossbar 27, forexample by a bolt or pivot pin.

In example embodiments, the left rear axle bracket 51′ further comprisesa right rear axle 52″ on which a right rear wheel 53″ is rotatablymounted. The left rear axle is generally secured to the vertical portionof the axle bracket and extends transversely away from the verticalportion in the direction opposite the top and bottom horizontal prongs.In example embodiments, the right rear axle 52″ is a bolt or axle pinhaving a head end and a threaded end, wherein the bolt is secured to theright rear axle bracket 51″ by its threaded end and the right rear wheel53″ is rotatably mounted on the bolt between the head and threaded ends.In other example embodiments, the right rear axle 52″ may be a fixedcomponent of the right rear axle 51″ which extends transverselytherefrom. Axle bracket 51″ also includes a rear tie-rod connection tabor member 54″ and a center tie-rod connection tab or member 55″, as bestshown in FIG. 5. The rear tie-rod connection tab 54″ is configured formounting thereon an end of the rear tie-rod 68 opposite the end mountedto the left rear tie-rod connection tab 54′, as described further below.Similarly, the center tie-rod connection tab 55″ is configured formounting thereon one end of a right center tie-rod 65″ as describedbelow.

According to example embodiments, the front and rear wheels 43′, 43″,53′, 53″ comprise 8-inch polyurethane or hard rubber tires. In alternateembodiments, the wheels comprise 12-inch air-filled or pneumatic knobbyall-terrain tires. The wheel diameters may vary depending on theapplication, for example between about 4-18 inches, between about 6-14inches, or between about 8-12 inches. The wheels may also comprise tiresmanufactured from other suitable materials known in the art.

The steering system 60 comprises a T-bar steering handlebar 61, asteering column 62, a steering column sleeve 63, a steering yoke ormount 64, center tie-rods 65′ and 65″, a steering or pitman arm 63B,front tie-rods 67′ and 67″, and a rear tie-rod 68, as shown in FIGS.1-5. T-bar handlebar 61 comprises a horizontal handle portion 61A and avertical column portion 61B. The horizontal handle portion includeshandle grips 61C′ and 61C″ secured to each end of the horizontal handleportion 61A, and a brake handle or lever 81 configured to operate abrake system 80, as described below. In example embodiments, verticalcolumn 61B extends transversely from the center of the horizontal handleportion 61A and includes a plurality of holes 61D along its length foradjusting the height of the handlebar 61, as shown in FIG. 2. In exampleembodiments, vertical column 61B has an outer diameter smaller than theinner diameter of the steering column 62, allowing the vertical columnto be inserted into or pass through within the steering column 62. Thesteering column 62 features a locking pin or through hole 62A whichaligns to the plurality of holes 61D on handlebar 61. In use, the heightof the handlebar 61 may be adjusted and locked or secured to auser-preferred height by aligning the locking pin hole 62A to one of theplurality of holes 61D on the handlebar and inserting or engaging alocking pin 62B, locking knob, locking button, or other suitable lockingmechanisms or systems for telescoping components. In exampleembodiments, the height of handle bar 61 and handle grips 61C′ and 61C″is adjustable between about 24-48 inches, or preferably about 30-41inches, from the ground or riding surface.

The steering column 62 generally has a tubular structure comprising atop end and a bottom end. The top end of the steering column isconfigured to receive the bottom end of the vertical portion 61B of thehandlebar 61, as described above. The bottom portion of the steeringcolumn 62 is inserted into the steering column sleeve 63. Steeringcolumn 62 is detachably locked or secured to the steering column sleeve63 such that they operate as a single component when assembled whileenabling disassembly as needed for easy storage and/or transportation.The steering column sleeve 63, having a top end and a bottom end,includes a top expanded lip 63A′ at its top end and a bottom expandedlip 63A″ at its bottom end, as best shown in FIG. 4. The steering columnsleeve 63 is passed through the head tube 22 and confined thereinbetween the top and bottom expanded lips of the steering column sleeve.The steering column sleeve is thereby prevented from being removed fromhead tube 22 while still being able to rotate axially therein.Effectively, handlebar 61, steering column 62, and steering columnsleeve 63 rotate or pivot axially in unison within the head tube 22during use. However, the handlebar and the steering column may bedisassembled from each other and from the steering column sleeve andhead tube as needed for, for example, easier storage and/ortransportation.

As best shown in FIG. 4, steering column sleeve 63 further comprises asteering arm 63B having a fixed end and a free end. Generally, the fixedend is welded, or otherwise attached, to the bottom expanded lip 63A″ ofthe steering column 63 and front tie-rods 67′ and 67″ are secured to theopposite, free end. In example embodiments, as the user rotates thehandlebar 61, steering column sleeve 63 is rotated about its axial axisinside head tube 22 thereby pivoting the steering arm 63B about itsfixed end. As the free end of the steering arm 63B moves arcuately, thefront tie-rods 67′ and 67″ are driven by the steering arm wherein theangular or rotational motion of the free end of the steering armtranslates the front tie-rods laterally. In the depicted embodiment, thesteering arm 63B extends transversely from the bottom expanded lip 63A″towards the rear of the knee walker. In the depicted embodiment,steering arm 63B comprises a Z-shaped profile but the profile need notbe so limited. The steering arm may comprise, for example, other flat,arced, or angled profiles, or any combination thereof.

As further shown in FIG. 4, steering arm 63B comprises a turn-stop post63C extending transversely therefrom. The turn-stop post is configuredto engage a turn-stop guide 22A mounted on the head tube 22. Theturn-stop guide protrudes laterally from head tube 22 and includes acontoured groove or notch between two extended protrusions which act asbumpers or backstops for the turn-stop post 63C. For example, when theuser rotates the handlebar 61, steering arm 63B pivots about the axialaxis of the steering column sleeve 63 and steering column 62. Duringnormal operations, the turn-stop post 63C moves freely within thecontoured notch of the turn-stop guide 22A. However, if the handlebar isrotated too much, the turn-stop post collides with the extendedprotrusions on either side of the contoured notch and the turn-stoppost, and effectively handlebar 61, is prevented from rotating anyfurther. In example embodiments, the turn-stop guide prevents the userfrom over-turning the handlebar thereby preventing unintended accidents,such as for example, abrupt turns or over-extending the center tie-bars.

As shown in FIG. 4, the steering yoke or mount 64 is affixed to the topend of steering column sleeve 63. Generally, center tie-rods 65′ and 65″are coupled to the steering mount 64 which transfers the rotationalmotion of the handlebar to the center tie-rods as described in moredetail below. In example embodiments, steering mount 64 comprises a mainbody with a pair of flanges or extensions 64A′ and 64A″ for mounting thefront, proximal ends of center tie-rods 65′ and 65″. The left verticalflange 64A′ is generally affixed to a first, left side of the steeringmount body. Similarly, the right vertical flange 64A″ is generallyaffixed to a second, right side of the steering mount body. The freeends of the left and right flanges 64A′, 64A″ are configured forsecuring thereon ends of center tie-rods 65′ and 65″, for example bymechanical fasteners, such as for example bolts or rivets. In otherexample embodiments, center tie-rods 65′ and 65″ may be welded, orotherwise permanently affixed, to flanges 64A′ and 64A″, respectively.In still other example embodiments, the front, proximal ends of thecenter tie-rods 65′ and 65″ may be mounted directly to the steeringmount 64.

Generally, knee walker 10 comprises a system or plurality of tie-rodconnectors which assist in the transfer of the operation and movement ofthe handlebar 61 to the front and rear axle assemblies 40′, 40″, 50′,and 50″. In example embodiments, front tie-rods 67′ and 67″—each havingtwo opposing ends—connect the front axle assemblies 40′ and 40″ to thesteering arm 63B, as best shown in FIGS. 3A-3B. For example, at itsfirst end, the left front tie-rod 67′ is secured to tie-rod connectormember 44′ of left front axle assembly 40′ while its second end issecured to the steering arm 63B. Similarly, the right front tie-rod 67″is secured to the steering arm 63B at its first end and secured totie-rod connector member 44′ of the right front axle assembly 40″ at itssecond end. As shown in FIGS. 2-5, the center tie-rods 65′ and 65″ actas linkages between the steering mount 64 and rear axle assemblies 50′and 50″. In example embodiments, both left and right center tie-rods 65′and 65″ comprise a first, front end and a second, rear end. The frontend of the left center tie-rod 65′ is secured to the left verticalflange 64A′ of steering mount 64 while the rear end is secured to thecenter tie-rod connector member 55′ of the left rear axle assembly 50′.Similarly, the front end of the right center tie-rod 65″ is secured tothe right vertical flange 64A″ of steering mount 64 while the rear endis secured to the center tie-rod connector member 55″ of the right rearaxle assembly 50″. As shown in FIG. 5, the rear tie-rod 68 connects theleft rear axle assembly 50′ to the right rear axle assembly 50″. Inexample embodiments, rear tie-rod 68 comprises a first, proximal end anda second, distal end wherein its first, proximal end is secured to therear tie-rod connector member 54′ of the left rear axle assembly 50′ andits second, distal end is secured to the rear tie-rod connector member54″ of the right rear axle assembly 50″.

In example methods or modes of use, knee walker 10 provides ambulatoryassistance to its users. Generally, the user places one knee on the kneecushion or knee-pad 31 to reduce any pressure or force applied to aninjured foot and/or lower leg while walking or moving by pushing offwith their uninjured foot and leg to roll the walker 10 forward or back.Handlebar 61 is provided for operating and maneuvering the knee walker.When fully assembled, handlebar 61, steering column 62, and steeringcolumn sleeve 63 are coupled together and rotate synchronously withinhead tube 22. As the user rotates the handlebar, the steering arm 63Band steering mount flanges 64A′ and 64A″ also hinge or rotate about theaxial axis of head tube 22. When the free end of the steering arm 63Bmoves, its arcuate motion pushes and pulls the front tie-rods 67′ and67″ laterally which in turn drives the front axle assemblies 40′ and40″. For example, as shown in FIG. 3A, when the handlebar 61 is rotatedcounter-clockwise, the steering arm 63B hinges about its fixed end, oraxial axis of steering column sleeve 63. As a result, the free end ofthe steering arm 63B pushes left front tie-rod 67′ towards the leftfront axle assembly 40′ wherein the left front tie-rod 67′ in turnpushes front tie-rod connector 44′ and drives left front axle assembly40′ to rotate about the left end 24A′ of front crossbar 24. At the sametime, as the steering arm 63B hinges about the axial axis of thesteering column sleeve, the free end of the steering arm pulls the rightfront tie-rod 67″ towards the left front axle assembly 40′ which in turncauses right front axle assembly 40″ to rotate counter-clockwise aboutright end 24A″ of front crossbar 24.

The rotation of the handlebar 61 also rotates the steering mount 64 andits flanges 64A′ and 64A″. As the left and right steering mount flanges64A′, 64A″ rotate about the axial axis of the steering column sleeve,one flange pulls one center tie-rod while the other flange pushes theother center tie-rod. For example, as shown in FIG. 3A, when thehandlebar is rotated counter-clockwise, left steering mount flange 64A′pulls left center tie-rod 65′ towards the front of the knee walker andright steering mount flange 64A″ pushes right center tie-rod 65″ towardsthe rear of the knee walker. In turn, the left center tie-rod pulls theleft center tie-rod connector 55′ towards the front of the knee walkerand thereby rotates the left rear axle assembly 50′ clockwise about leftend 27A′ of rear crossbar 27. At the same time, the right center tie-rod65″ pushes the left center tie-rod connector 55″ towards the rear of theknee walker and thereby rotates the right rear axle assembly 50″clockwise about right end 27A″ of rear crossbar 27. The rear tie-rod 68secured to rear tie-rod connector members 54′ and 54″ providesadditional linkage between the rear axle assemblies 50′ and 50″. Theadditional linkage reinforces the interconnection between the steeringmount, center tie-rods, and rear axle assemblies, and improves theresponsiveness of the overall system.

According to example embodiments, knee walker 10 further includes abrake system 80. The brake system comprises a brake handle 81; brakecables or lines 82A, 82B′, and 82B″; brake line anchors 84′ and 84″;brake levers 85′ and 85″; brake housings 86′ and 86″; and brake rotorsor discs 87′ and 87″. As shown in FIG. 2, brake handle 81 is generallysecured to the handlebar 61 near one of the handle grips. For example,in the depicted embodiment, the brake handle is attached to thehandlebar near the right handle grip 61C″. However, the brake handle maybe provided near the left handle grip 61C′, or near both left and righthandle grips.

In example embodiments, a single brake line 82A extends out from brakehandle 81 but is later split into two separate brake lines 82B′ and82B″. Brake line 82B′ leads to the left brake housing 86′ attached tothe left rear axle bracket 51′. Brake line 82B″ leads to the right brakehousing 86″ attached to the right rear axle bracket 51″. The brake linesare generally sheathed inside a polyurethane sheath or sleeve 83;however, sheath 83 may also be made from natural or synthetic rubbers,fibers, or other suitable materials. In example embodiments, brake lines82B′ and 82B″ are secured to brake levers 85′ and 85″, respectively, asshown in FIG. 5. Brake levers 85′ and 85″ are pivotally mounted to thebrake housings 86′ and 86″, respectively. The brake housings enclosebrake calipers (not shown) which are actuated by the brake levers andare configured to apply pressure to the brake rotors 87′ and 87″ to slowor stop the rear wheels as needed. The brake discs are affixed to therear axles such that motion of the rear wheels are locked to the motionof the brake discs. In other words, for example, the left brake disc andleft rear wheel rotate together as a unitary body. In exampleembodiments, brake lines 82A, 82B′ and 82B″ are typically made fromtwisted or braided steel but may also be constructed from other metals,natural and/or synthetic fibers and fiber composites, plastics, or othersuitable materials.

In use, the user clenches or contracts the brake handle 81 by squeezingtheir hand to apply the brakes as needed. The contraction of the brakehandle causes brake lines 82B′ and 82B″ to be pulled forward towards thefront of the knee walker. The pull of the brake lines causes brakelevers 85′ and 85″ to pivot which in turn actuates the brake caliperscausing them to engage and apply resistive pressure on the brake rotors.Because brake lines 82B′ and 82B″ are split from a single brake line82A, actuation of the left and right brakes occurs simultaneously.

According to another example embodiment of the present invention, andwith reference to FIG. 6, a knee walker 100 comprises a four-wheelcable-actuated steering system. The cable steering system generallyreplaces the center tie-rods of knee walker 10 with durable cables, forexample made from twisted or braided steel. Knee walker 100 comprises acenter crossbar 126 having a front, proximal end and a rear, distal end.At its rear, distal end, the center crossbar 126 comprises a hingemechanism 126A. The hinge mechanism is configured to receive and securea rear axle assembly 150. The rear axle assembly comprises a rearcrossbar 127 having a left, first end and a right, second end, a leftrear wheel 153′ rotatably mounted to the left end of the rear crossbar127, and a right rear wheel 153″ rotatably mounted to the right end ofthe rear crossbar 127. The rear crossbar 127 is pivotally secured to thehinge mechanism 126A, for example by a pivot pin or bolt, about itscenter. The rear crossbar 127 further comprises steering cable anchorpoints 167′ and 167″ equal distances apart from the rear crossbar'scenter. In the example embodiment, rear crossbar 127 has a tubularstructure and spans about 4-12 inches, preferably about 5-10 inches, andmore preferably about 6-8 inches. The cable anchors 167′ and 167″ aresecured about 1-4 inches, or preferably 2-3 inches, from the rearcrossbar's center.

According to the example embodiment, the knee walker comprises twosteering cables—a first steering cable 163′ and a second steering cable163″, as shown in FIG. 6. The steering cables are typically made fromtwisted or braided steel but may also be constructed from other metals,natural and/or synthetic fibers and fiber composites, plastics, or othersuitable materials. The first steering cable 163′ is secured to the leftsteering mount flange 162′ at its first, front end and to the right rearaxle anchor 167″ at its second, rear end. The second steering cable 163″is secured to the right steering mount flange 162″ at its first, frontend and left rear axle anchor 167′ at its second, rear end. Bothsteering cables 163′ and 163″ are loosely retained adjacent to thecenter crossbar 126 at predetermined points along its length. In thedepicted embodiment, steering cables 163′ and 163″ are guided throughretaining elements or points 164′, 164″, 166′, and 166″ to maintain thesteering cables along the length of the center crossbar and prevent anyunwanted entanglement. In example embodiments, the steering cables arefurther at least partially encased in a polyurethane sheaths or sleeves165′ and 165″. In other example embodiments, sheaths 165′ and 165″ maybe made from natural or synthetic rubbers, fibers, or other suitablematerials.

According to the depicted embodiment, crossing of the steering cables163′ and 163″ across the center crossbar forces the rear axle assembly150 to rotate in the opposite direction from the handlebar 161 and frontaxle assemblies 140′ and 140″. The opposing rotations of the front andrear axle assemblies allow knee walker 100 to achieve a smaller turningradius. For example, when the user rotates the steering handlebar 161 inthe clockwise direction, front axle assemblies 140′ and 140″ are rotatedin the same clockwise direction via tie rods 177′ and 177″.Simultaneously, the steering mount is rotated in the same clockwisedirection which rotates forward the right steering mount flange 162″placing steering cable 163″ under tension. As a result of the tension inthe steering cable 163″, the left anchor point 127′ and left end of therear crossbar 127 is pulled forward, rotating the rear axle assembly 150in a counter-clockwise direction, opposite the front axle assemblies140′ and 140″. Conversely, turning the handlebar 161 in thecounter-clockwise direction causes the rear axle assembly 150 to rotatein the opposite, clockwise direction. Opposing rotations of the frontand rear axle assemblies eliminate rear wheel drag and improve theeffective turning radius of the knee walker. In this manner, tighterturns and improved maneuverability, relative to previously known kneewalkers, are achieved. Improved stability may also be provided, forexample due to shifting the turning or yaw axis toward, or coincidentwith, the center of gravity of the walker and person carried thereon,for example to a position at or around the knee cushion.

In some example embodiments, the knee walker may comprise a steeringsystem comprising only cables or chains. In other example embodiments,the knee walker may comprise a steering system comprising arack-and-pinion. In yet other example embodiments, the knee walker maycomprise steering systems incorporating hydraulics, chain-and-gear,and/or belt-and-wheel mechanisms operably configured to providefour-wheel steering. Motors and electronic actuators may be furtherincorporated to fully or partially automate the operation of thesteering system.

While the invention has been described with reference to exampleembodiments, it will be understood by those skilled in the art that avariety of modifications, additions and deletions are within the scopeof the invention, as defined by the following claims.

What is claimed is:
 1. A knee walker with four-wheel steeringcomprising: a body frame, two front axle assemblies and two rear axleassemblies pivotally mounted to the body frame, a knee-pad assembly, anda steering system; wherein the steering system is configured to drivethe two front axle assemblies in a first rotational direction and thetwo rear axle assemblies in an opposite second rotational direction; andwherein the two front axle assemblies are hingeably mounted to oppositeends of a front crossbar and the two rear axle assemblies are hingeablymounted to opposite ends of a rear crossbar.
 2. The knee walker of claim1, wherein the steering system comprises a handlebar, a steering column,a steering sleeve, and a plurality of linkage mechanisms.
 3. The kneewalker of claim 2, wherein the linkage mechanisms are tie-rods.
 4. Theknee walker of claim 2, wherein the linkage mechanisms are cables. 5.The knee walker of claim 2, wherein the linkage mechanisms comprisetie-rods and cables.
 6. The knee walker of claim 2, wherein the twofront axle assemblies and the two rear axle assemblies are cooperativelyconnected to the steering column, steering sleeve, and handlebar by theplurality of linkage mechanisms.
 7. The knee walker of claim 6, whereinthe two rear axle assemblies are cooperatively connected to one anotherby one of the plurality of linkage mechanisms.
 8. The knee walker ofclaim 1, further comprising at least one brake assembly.
 9. The kneewalker of claim 8, comprising two brake assemblies, wherein one brakeassembly is mounted to each of the two rear axle assemblies and whereinthe two brake assemblies are operated simultaneously.
 10. A four-wheelknee walker comprising a body frame having a front end and a rear end,the body frame comprising a kneeling cushion attached thereto betweenits front and rear ends; a left front axle assembly and a right frontaxle assembly, with a left front wheel rotatably mounted on the leftfront axle assembly, and a right front wheel rotatably mounted on theright front axle assembly; a left rear axle assembly and a right rearaxle assembly, with a left rear wheel rotatably mounted on the left rearaxle assembly, and a right rear wheel rotatably mounted on the rightrear axle assembly; and a steering system, the steering systemcomprising a steering column having a handlebar, a steering mount, and asteering arm, and a plurality of tie-rods; wherein a first tie-rod linksthe left front axle assembly to the steering arm, a second tie-rod linksthe right front axle assembly to the steering arm, a third tie-rod linksthe left rear axle assembly to the steering mount, a fourth tie-rodlinks the right rear axle assembly to the steering mount, and a fifthtie-rod links the left rear axle assembly to the right rear axleassembly; wherein the handlebar, the steering mount, and the steeringarm operate in unison to control the plurality of tie-rods; and whereinthe plurality of tie-rods control the turning of the left front axleassembly and the right front axle assembly in unison in a firstdirection while turning the left rear axle assembly and right rear axleassembly in a second direction opposite the first direction.
 11. Thefour-wheel knee walker of claim 10, further comprising a brake systemwherein the brake system comprises: a first brake mounted on the leftrear axle assembly and a second brake mounted on the right rear axleassembly; and a brake handle mounted on the handlebar, wherein the firstand second brakes are actuated by the brake handle simultaneously. 12.The four-wheel knee walker of claim 11, wherein the body frame comprisesa fixed rear crossbar having a first end and second end and wherein theleft rear axle assembly and right rear axle assembly are hingeablymounted to the first and second ends of the rear crossbar, respectively.